Method for carrying out plasma processing on a wafer under Run-to-Run control by using a plasma processing apparatus having a plasma processing chamber, a process monitor which monitors a condition in the plasma processing chamber, and an actuator which controls parameters which are constituent elements of a plasma processing condition. The method includes the steps of making one of the parameters a (N−1)th manipulated variable, calculating a first difference between a process monitor value in the plasma processing obtained by the process monitor and a desired value of the process monitor value in the plasma processing, calculating a correction amount of the (N−1)th manipulated variable on the basis of the first difference and a previously obtained correlation between the process monitor value in the plasma processing and the (N−1)th manipulated variable, wherein N is a natural number equal to or larger than 2.
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1. A plasma processing method for carrying out plasma processing on a wafer under Run-to-Run control by using a plasma processing apparatus having a plasma processing chamber in which plasma processing is carried out, a process monitor which monitors a condition in the plasma processing chamber, and an actuator which controls parameters which are constituent elements of a plasma processing condition, the method comprising the steps of: making one of the parameters a (N−1)th manipulated variable; calculating a first difference between a process monitor value in the plasma processing obtained by the process monitor and a desired value of the process monitor value in the plasma processing; calculating a correction amount of the (N−1)th manipulated variable on the basis of the first difference and a previously obtained correlation between the process monitor value in the plasma processing and the (N−1)th manipulated variable; wherein N is a natural number equal to or larger than 2, determining whether or not the (N−1)th manipulated variable exceeds a limit value of the (N−1)th manipulated variable on the basis of the correction amount of the (N−1)th manipulated variable; calculating an Nth difference between the monitor value in the plasma processing and a monitor value calculated, as a case that the (N−1)th manipulated variable is a limit value, from the previously obtained correlation between the monitor value in the plasma processing and the (N−1)th manipulated variable; and calculating a correction amount of the Nth manipulated variable on the basis of the previously obtained correlation between the monitor value in the plasma processing and the Nth manipulated variable and the Nth difference; and wherein determining that the (N−1)th manipulated variable exceeds a limit value of the (N−1)th manipulated variable on the basis of the correction amount of the (N−1)th manipulated variable, correcting a plasma processing condition of a next wafer on the basis of the correction amount of the (N−1)th manipulated variable which causes the (N−1)th manipulated variable to be set to the limit value of the (N−1)th manipulated variable and the correction amount of the calculated Nth manipulated variable.
A method for controlling a plasma processing apparatus (chamber, monitor, actuator) performing wafer processing. It adjusts plasma condition parameters using "Run-to-Run" control. A parameter is selected as the (N-1)th variable, where N >= 2. The difference between a process monitor value and its desired value is calculated. A correction is made to the (N-1)th variable based on this difference and a pre-existing correlation. If this correction exceeds a limit of the (N-1)th variable, a new difference is calculated using the limit value. A correction is then calculated for an Nth variable based on its correlation with the monitor value. This adjusts the plasma processing condition for the next wafer, using both the (N-1)th variable's limit and the calculated Nth variable correction.
2. The plasma processing method according to claim 1 , further comprising the steps of: determining whether or not the Nth manipulated variable exceeds a limit value of the Nth manipulated variable on the basis of the correction amount of the Nth manipulated variable; calculating an (N+1)th difference between the monitor value in the plasma processing and a monitor value calculated, as a case that the Nth manipulated variable is a limit value, from the previously obtained correlation between the monitor value in the plasma processing and the Nth manipulated variable; and calculating a correction amount of the (N+1)th manipulated variable on the basis of the preciously obtained correlation between the monitor value in the plasma processing and the (N+1)th manipulated variable and the (N+1)th difference, and wherein, when determining that the (N−1)th manipulated variable exceeds the limit value of the (N−1)th manipulated variable on the basis of the correction amount of the (N−1)th manipulated variable, and determining that the Nth manipulated variable does not exceed the limit value of the Nth manipulated variable on the basis of the correction amount of the Nth manipulated variable, setting the correction amount of the (N+1)th manipulated variable to zero, and correcting the plasma processing condition of the next wafer on the basis of the correction amount of the (N−1)th manipulated variable which causes the (N−1)th manipulated variable to be set the limit value of the (N−1)th manipulated variable and the correction amount of the calculated Nth manipulated variable.
The plasma processing method of claim 1 further checks if the Nth manipulated variable's correction exceeds its limit. If it does, it calculates an (N+1)th difference using the Nth variable's limit. It then calculates a correction for an (N+1)th variable based on its correlation. If the (N-1)th variable exceeds its limit (from claim 1), but the Nth variable does NOT exceed its limit, the (N+1)th variable's correction is set to zero. The plasma processing condition of the next wafer is adjusted using the limited (N-1)th variable correction and the Nth variable correction. This avoids unnecessary adjustments when one parameter hits its limit.
3. The plasma processing method according to claim 1 , wherein the N is 2, and the plasma processing is a plasma etching.
The plasma processing method described in claim 1, where a plasma processing apparatus (chamber, monitor, actuator) performs wafer processing and adjusts plasma conditions using "Run-to-Run" control by correcting plasma parameters using process monitor feedback and pre-existing process correlations. In this case, N=2, and the plasma processing being performed is plasma etching. The method involves calculating corrections to a (N-1)=1st variable and (if necessary due to limit conditions on the 1st variable) a 2nd variable to control the plasma etching process on a wafer.
4. The plasma processing method according to claim 2 , wherein the N is 2, and the plasma processing is a plasma etching.
The plasma processing method of claim 2, which builds upon claim 1, further checks if the Nth manipulated variable's correction exceeds its limit. If it does, it calculates an (N+1)th difference using the Nth variable's limit and sets the (N+1) variable to zero. In this case, N=2, and the plasma processing being performed is plasma etching. The method adjusts plasma conditions for a plasma etching process on a wafer, with limit checks and cascading corrections to (N-1)=1st, N=2nd, and (N+1)=3rd variables based on process monitoring and pre-existing process correlations.
5. The plasma processing method according to claim 3 , wherein the (N−1)th manipulated variable is a flow rate of a gas provided in the plasma processing chamber.
The plasma etching method as described in claim 3 (N=2), where a plasma processing apparatus (chamber, monitor, actuator) etches wafers and adjusts etching conditions using "Run-to-Run" control, calculates corrections to a 1st and 2nd variable using process monitor feedback and pre-existing process correlations, also wherein the (N-1)th = 1st manipulated variable is the flow rate of a gas provided into the plasma processing chamber.
6. The plasma processing method according to claim 3 , wherein one of the (N−1)th and the Nth manipulated variable is a flow rate of a gas provided in the plasma processing chamber.
The plasma etching method as described in claim 3 (N=2), where a plasma processing apparatus (chamber, monitor, actuator) etches wafers and adjusts etching conditions using "Run-to-Run" control, calculates corrections to a 1st and 2nd variable using process monitor feedback and pre-existing process correlations, also wherein either the (N-1)th = 1st or the Nth = 2nd manipulated variable is the flow rate of a gas provided into the plasma processing chamber.
7. The plasma processing method according to claim 5 , wherein the other of the (N−1)th and the Nth manipulated variable is a radio frequency bias power provided in the plasma processing chamber.
The plasma processing method described in claim 5, where the (N-1)th manipulated variable (where N=2) is the gas flow rate into the plasma processing chamber. The other manipulated variable, the Nth manipulated variable (2nd variable) is a radio frequency bias power provided into the plasma processing chamber. The etching process is adjusted by controlling gas flow and RF bias power using "Run-to-Run" control based on process monitoring and pre-existing process correlations.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
August 1, 2014
November 21, 2017
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